Add Selector.union() classmethod, abbreviate long selector string in …

…Selector.__repr__(), use SelectorMethods.collapse() in Selector when computing string corresponding to expanded selectors.

neurokernel/plsel.py

@@ -70,7 +70,7 @@ def __init__(self, s):
         else:
             self._expanded = tuple(SelectorMethods.expand(s))
             self._max_levels = max(map(len, self._expanded))
-            #XXX
+            self._str = SelectorMethods.collapse(self._expanded)
 
     @property
     def nonempty(self):
@@ -117,7 +117,7 @@ def add(cls, *sels):
         Returns
         -------
         result : Selector
-            Selector containing all of the port identifiers comprised by the 
+            Selector containing all of the port identifiers comprised by all of the 
             arguments.
         """
 
@@ -136,6 +136,18 @@ def add(cls, *sels):
     def concat(cls, *sels):
         """
         Concatenate the identifiers in multiple selectors elementwise.
+
+        Parameters
+        ----------
+        sels : Selector
+            Selector instances.
+
+        Returns
+        -------
+        result : Selector
+            Each port identifier in the returned Selector is equivalent to 
+            the elementwise concatenation of the identifiers in the listed
+            Selector instances.
         """
 
         out = cls('')
@@ -169,6 +181,22 @@ def prod(cls, *sels):
                 for i in itertools.product(*[s.expanded for s in sels]))
         return out
 
+    @classmethod
+    def union(cls, *sels):
+        """
+        Compute the union of the identifiers in multiple selectors.
+        """
+
+        out = cls('')
+        out._expanded = \
+            tuple(sorted(reduce(lambda a, b: set(a.expanded).union(b.expanded), sels)))
+        try:
+            out._max_levels = max([s.max_levels for s in sels if s.nonempty])
+        except ValueError:
+            out._max_levels = 0
+        out._str = SelectorMethods.collapse(out._expanded)
+        return out
+
     def __add__(self, y):
         return self.add(self, y)
 
@@ -186,7 +214,10 @@ def __iter__(self):
             yield ((),)
 
     def __repr__(self):
-        return 'Selector(\'%s\')' % self._str
+        if len(self._str) <= 100:
+            return 'Selector(\'%s\')' % self._str
+        else:
+            return 'Selector(\'%s\')' % (self._str[0:25]+' ... '+self._str[-25:])
 
 class SelectorParser(object):
     """

tests/test_plsel.py

@@ -126,6 +126,24 @@ def test_selector_iter(self):
         self.assertSequenceEqual([s for s in sel],
                                  [((),)])
 
+    def test_selector_union_empty(self):
+        a = Selector('')
+        b = Selector('')
+        c = Selector.union(a, b)
+        assert len(c) == 0
+        assert c.expanded == ((),)
+        assert c.max_levels == 0
+        assert c.str == ''
+
+    def test_selector_union_nonempty(self):
+        a = Selector('/x[0:3]')
+        b = Selector('/x[2:5]')
+        c = Selector.union(a, b)
+        assert len(c) == 5
+        assert c.expanded == (('x', 0), ('x', 1), ('x', 2), ('x', 3), ('x', 4))
+        assert c.max_levels == 2
+        assert c.str == '/x/0,/x/1,/x/2,/x/3,/x/4'
+
 class test_path_like_selector(TestCase):
     def setUp(self):
         self.df = df.copy()